1. Technical Field
This invention relates to a battery system comprising battery means for supplying operating power during battery operation of a battery power receiving device; a battery information circuit carried as a unit with the battery means for assembly with the battery power receiving device; said battery information circuit having memory cells and being capable of communicating information with the battery power receiving device.
The invention also relates to a battery comprising battery means for supplying operating power during battery operation of a battery power receiving device; a battery information circuit carried as a unit with the battery means; said battery information circuit having memory cells and being capable of communicating information with the battery power receiving device.
Moreover, the invention relates to a method of storing information in a battery information circuit carried as a unit with battery means for assembly with a battery power receiving device and of communicating information between the battery information circuit and the battery power receiving device.
2. Description of Related Art
The development of cellular telephone technology has created a similar need for development in the area of batteries and battery packs, and more specifically for amethod of communicating battery information e.g. in a cellular telephone. The telephones must utilise batteries in order to provide mobile capabilities. The battery is critical to the user of a cellular telephone, since the battery allows the user to move about freely without being tied to a stationary power source.
Thus, in order to fully maximise the use of a cellular telephone, it is important, from a first point of view that a user achieves maximum performance from an attached battery. This may be achieved by e.g. correctly charging the battery and always being able to identify the exact charging status of the battery. This enables a user to know how much standby time is left on the phone. This type of information enables a user to intelligently decide whether the charge in the battery is sufficient for his needs, or whether charging of the battery is required.
However, from a second point of view and in order to aid the user in achieving such maximum performance from the battery, it is important that the cellular telephone itself is able to achieve maximum performance from an attached battery e.g. by charging and discharging the battery according to given specifications. Such specifications are typically stated as parameters and can comprise minimum and maximum charging and discharging temperatures, maximum charging current and voltage, etc.
Thus the battery system must be capable of handling such various types of parameters which will often have parameter values within different ranges e.g. temperatures between -20 and 100.degree. C., currents between 200 and 4000 mA, etc.
Due to the fact that such specifications are battery specific in order to achieve maximum performance, a well-known solution within the field of battery powered equipment is to provide a so-called `smart` battery or battery system. Such a battery system comprises a battery and a microprocessor capable of providing advanced battery information to the battery powered equipment e.g. a cellular mobile telephone.
Battery systems used in small-sized hand held electronic equipment especially mobile phones differ from ordinary battery systems in that low weight and hours of use, i.e. time the equipment can be used without having to recharge the battery, are extremely important competition parameters. Further, price is an extremely important parameter in the competition with other vendors of mobile telephones and accessories for mobile telephones, since most vendors are capable of providing almost the same functionality of the equipment and in that such equipment is sold as consumer products. Consequently, there is an extremely great desire for a low-cost battery system solution.
U.S. Pat. No. 4,709,202 discloses a battery powered system comprising a microprocessor permanently secured to the battery so as to receive operating power therefrom. The performance of a given battery in actual use can be accurately judged since the battery system itself can maintain a count of accumulated hours of use of the battery powered system. Further, the battery system can maintain other relevant parameters e.g. battery temperature, battery output voltage, and battery capacity based on a charging cycle. Thus, from this patent it is known to communicate battery information as such using ordinary communications techniques.
However, this patent does not concern the fact that the storage capacity for storing battery information within the battery system should be limited as much as possible in order to obtain a low-cost embodiment.
Further, typically, the communication between the battery system and the battery powered system is implemented via a simple half-duplex communications line only capable of transferring data with a few hundred bytes per second. Hence, if much superfluous battery information is transmitted back and forth, the system performance may be degraded unnecessarily.